Beverage capsule with anti-dripping membrane

ABSTRACT

The present invention concerns a beverage capsule ( 11 ) comprising capsule side walls ( 20 ), a capsule top, and a capsule bottom ( 21 ) having a dispensing outlet ( 22 ), that define a chamber for containing a food or beverage precursor ingredient soluble and/or extractable when a fluid is injected inside said chamber under pressure, said capsule ( 11 ) further comprising a pressure-sensitive membrane ( 25 ), characterized in that said pressure-sensitive membrane ( 25 ) comprises at least one weakened or precut zone defining a non-reclosable opening ( 26 ) which: (i) elastically and plastically opens, respectively widens when the fluid pressure inside said capsule reaches a predetermined value between 0.5 and 20 bar relative pressure, and then (ii) maintains a widen configuration after the fluid pressure within the chamber is released to an atmospheric pressure value, such that the width of said at least one opening ( 26 ) does not exceed 1 mm.

FIELD OF THE INVENTION

The present invention concerns an ingredient capsule for use in a foodpreparation machine, for instance in a liquid food preparation machine.

BACKGROUND OF THE INVENTION

Beverage preparation machines are well known in the food science andconsumer goods area. Such machines allow a consumer to prepare at home agiven type of beverage, for instance a coffee-based beverage, e.g. anespresso or a brew-like coffee cup.

Today, most beverage preparation machines for in-home beveragepreparation comprise a system made of a machine which can accommodateportioned ingredients for the preparation of the beverage. Such portionscan be soft pods or pads, or sachets, but more and more systems usesemi-rigid or rigid portions such as rigid pods or capsules. In thefollowing, it will be considered that the beverage machine of theinvention is a beverage preparation machine working with a rigid orsemi-rigid capsule.

The machine comprises a receptacle or cavity for accommodating saidcapsule and a fluid injection system for injecting a fluid, preferablywater, under pressure into the capsule. Water injected under pressure inthe capsule, for the preparation of a coffee beverage according to thepresent invention, is preferably hot, that is to say at a temperatureabove 70° C. However, in some particular instances, it might also be atambient temperature, or even chilled. The pressure inside the capsulechamber during extraction and/or dissolution of the capsule contents istypically about 1 to about 8 bar for dissolution products and about 2 toabout 12 bar for extraction of roast and ground coffee. Such apreparation process differs a lot from the so-called “brewing” processof beverage preparation—particularly for tea and coffee, in that brewinginvolves a long time of infusion of the ingredient by a fluid (e.g. hotwater), whereas the beverage preparation process allows a consumer toprepare a beverage, for instance coffee, within a few seconds.

The principle of extracting and/or dissolving the contents of a closedcapsule under pressure is known, and consists typically of inserting thecapsule in a receptacle or cavity of a machine, injecting a quantity ofpressurized water into the capsule, generally after piercing a face ofthe capsule with a piercing injection element such as a fluid injectionneedle mounted on the machine, so as to create a pressurized environmentinside the capsule either to extract the substance or dissolve it, andthen release the extracted substance or the dissolved substance throughthe capsule. Capsules allowing the application of this principle havealready been described for example in applicant's European patents no EP1472156 B1, and EP 1784344 B1.

Machines allowing the application of this principle have already beendescribed for example in patents CH 605 293 and EP 242 556. According tothese documents, the machine comprises a receptacle or cavity for thecapsule and a perforation and injection element made in the form of ahollow needle comprising in its distal region one or more liquidinjection orifices. The needle has a dual function in that it opens thetop portion of the capsule on the one hand, and that it forms the waterinlet channel into the capsule on the other hand.

The machine further comprises a fluid tank—in most cases this fluid iswater—for storing the fluid that is used to dissolve and/or infuseand/or extract under pressure the ingredient(s) contained in thecapsule. The machine comprises a heating element such as a boiler or aheat exchanger, which is able to warm up the water used therein toworking temperatures (classically temperatures up to 80-90° C.).Finally, the machine comprises a pump element for circulating the waterfrom the tank to the capsule, optionally though the heating element. Theway the water circulates within the machine is e.g. selected via aselecting valve means, such as for instance a peristaltic valve of thetype described in applicant's European patent application EP 2162653 A1.

When the beverage to be prepared is coffee, one interesting way toprepare the coffee is to provide the consumer with a capsule containingroast and ground coffee powder, which is to be extracted with hot waterinjected therein.

In many instances, the machine comprises a capsule holder for holding acapsule, which is intended to be inserted in and removed from acorresponding cavity or receptacle of the machine. When a capsule holderis loaded with a capsule and inserted within the machine in a functionalmanner, the water injection means of the machine can fluidly connect tothe capsule to inject water therein for a food preparation, as describedabove. A capsule holder was described for example in applicant'sEuropean patent EP 1967100 B1.

Capsules have been developed for such an application of foodpreparation, and in particular for beverage preparation, which aredescribed and claimed in applicant's European patent EP 1784344 B1, orin European patent application EP 2062831.

In short, such capsules comprise typically:

-   -   a hollow body and an injection wall which is impermeable to        liquids and to air and which is attached to the body and adapted        to be punctured by e.g. an injection needle of the machine,    -   a chamber containing a bed of roast and ground coffee to be        extracted, or a soluble ingredient or mix of soluble        ingredients,    -   an aluminium membrane disposed at the bottom end of the capsule,        closing the capsule, for retaining the internal pressure in the        chamber.

The aluminium membrane is designed for being pierced with piercing meansthat are either integral with the capsule, or located outside of saidcapsule, for example within a capsule holder of the machine.

The piercing means are adapted for piercing dispensing holes in thealuminium membrane when the internal pressure inside the chamber reachesa certain pre-determined value.

Also, optionally, the capsule can further comprise means configured tobreak the jet of fluid so as to reduce the speed of the jet of fluidinjected into the capsule and distribute the fluid across the bed ofsubstance at a reduced speed.

Capsules of the prior art feature an injection wall or membrane(referred to as top membrane) which is to be pierced by a fluidinjection element (e.g. needle) of a beverage preparation machine beingpart of a fluid system. When fluid is injected in the capsulecompartment, a pressure is built up, which serves as an extraction meansfor extracting and/or dissolving ingredients contained inside thecapsule, as described above. Such ingredients can be for instance a bedof roast and ground coffee. Alternatively or in combination with roastand ground coffee, the ingredients can comprise soluble ingredients,such as for instance beverage premixes.

At the end of the beverage production process the capsule is opened bothat an inlet side and at an outlet side. Although the biggest portion ofthe liquid introduced into the interior of the capsule will be drainedfrom the water, there will always some residual liquid remaining in thecapsule after the beverage production process.

Particularly when the capsule is then taken out from the beverageproduction machine, there is the problem of water or beverage drippinge.g. from the water inlet side of the capsule. Such dripping forces toconsumer to leave ones cup below the capsule dispensing outlet severalseconds after the completion of the dispensing, which is undesirable. Insome instances, dripping can also cause messiness in or around themachine, in case the consumer has removed the cup from below thedispensing outlet, which is also undesirable. It is thought that thisdripping is particularly promoted by air entering the capsule from thebeverage outlet side.

The invention therefore has the object to reduce the risk of residualliquid dripping out of the capsule after the completion of the beverageproduction process.

SUMMARY OF THE INVENTION

The objective set out above is met with a beverage capsule comprisingcapsule side walls, a capsule top, and a capsule bottom having adispensing outlet, that define a chamber for containing a food orbeverage precursor ingredient soluble and/or extractable when a fluid isinjected inside said chamber under pressure, said capsule furthercomprising a pressure-sensitive membrane located between said ingredientand said dispensing outlet, characterized in that saidpressure-sensitive membrane comprises at least one weakened or precutzone defining a non-reclosable opening which:

(i) elastically and plastically opens, respectively widens when thefluid pressure inside said capsule reaches a predetermined value between0.5 and 20 bar relative pressure, preferably between 1.0 and 15 bar, andthen

(ii) maintains a widen configuration after the fluid pressure within thechamber is released to an atmospheric pressure value, such that thewidth of said at least one opening does not exceed 1 mm, preferably thatdoes not exceed 0.5 mm.

In a highly preferred embodiment of the invention, said at least oneprecut opening is a slit having a length to width ratio comprisedbetween 1:1 and 1000:1, preferably comprised between 1:1 and 50:1, morepreferably comprised between 5:1 and 20:1.

Alternatively, the precut opening can take the form of a cross, anarcuate segment, a zigzag, or any other shape suitable to provide themechanical properties mentioned above, i.e. being able to sufficientlyopen under pressure during dispensing of the beverage, and thenpartially reclose, or otherwise maintain a widen configuration whenin-capsule pressure drops down to a value substantially equivalent tothe atmospheric pressure. Such alternative shapes can be beneficial inallowing products to flow and be dispensed to a consumer cup, which havevarious viscosities, and optionally contain small edible particles, likefor instance croutons, small herb or fruit pieces, etc., while providinggood anti-dripping properties to the capsule after dispensing of thebeverage.

In a highly preferred embodiment of the invention, and in order toachieve the opening, widening and reclosability properties mentionedabove, the material used for the pressure-sensitive membrane is has thefollowing physical characteristics: a Young's modulus comprised withinthe range of 800 MPa to 5000 MPa, a Yield point comprised within therange of 10 MPa to 50 MPa, and a melting point comprised within therange of 100° C. to 200° C., preferably within the range of 140° C. to180° C., a thickness that is comprised between 50 μm and 800 μm,preferably between 100 μm and 600 μm.

Advantageously, the pressure-sensitive membrane is made out of at leastone layer of a thermoplastic material, selected within the list of:polyethylene (PE), polypropylene (PP), ethylene vinyl alcohol (EVOH),polystyrene (PS), or a combination thereof.

Also preferably, the capsule side walls and capsule top are moisture andoxygen permeable, and wherein said capsule further comprises apierceable or tearable moisture and oxygen barrier bottom membrane, suchthat the capsule chamber is closed.

The bottom membrane is preferably openable by piercing by action of anpiercing element located within or outside of the capsule vicinity.

In a preferred embodiment, the beverage prepared within said capsule hasa viscosity comprised between 0.1 and 1.00 mPa·s.

The capsule of the invention preferably comprises a precursor ingredientfor making a beverage comprised within the list of: soups, fruit juices,vegetable juices, bouillons, coffee, chocolate, tea, milk or creamer, ora combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the description of thepresently preferred embodiments which are set out below with referenceto the drawings in which:

FIG. 1 is a perspective side view of a beverage preparation machinesuitable for use with a capsule according to the invention;

FIG. 2 is a schematic enlarged view of the interior of a brewing head ofthe machine illustrated in FIG. 1;

FIG. 3 is a schematic perspective cut view showing the interior of acapsule according to the invention;

FIG. 4 is a schematic split view similar to FIG. 3;

FIG. 5 is a top view of a dispensing membrane with slits according tothe invention;

FIG. 6 is an enlarged perspective view of the bottom portion of acapsule according to the invention, wherein the slits of the bottomdispensing membrane are closed;

FIG. 7 is a similar view to FIG. 6, wherein the slits of the bottomdispensing membrane are open;

FIG. 8 is an enlarged top perspective view of the bottom part of acapsule according to the invention, wherein a slit is shown in its openconfiguration;

FIG. 9 is a schematic partially cut view of an alternative embodiment ofthe capsule according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The capsule according to the present invention is meant to be used witha beverage preparation machine illustrated in FIG. 1, thus forming abeverage preparation system.

As shown in FIG. 1, the machine 1 comprises a machine body 2, a waterreservoir 3 that can be removed from the machine body 2 for refill. Thebody 2 comprises a on/off push button 4. The machine 1 further comprisesa extraction head 5. The head 5 comprises a water temperature selectorfor hot or cold water taking the form of two buttons 6 (one forselecting a hot beverage, the other for cold), a locking lever 7, and anopening for insertion of a capsule holder 8. The machine 1 furthercomprises a cup tray 9, for holding a cup under the extraction head. Themachine further comprises a control panel 10 comprising a selector wheelfor selecting for instance the volume of beverage to be dispensed, aswell as a screen, wherein data about the beverage preparation settingsare represented.

The capsule holder 8 is adapted to receive a capsule 11. A view of thecapsule holder 8 is shown in FIG. 2, wherein a capsule 11 is disposed,said holder 8 and capsule 11 being inserted into the correspondingreceptacle of the extraction head as illustrated in FIG. 1. The capsuleholder 8 comprises a body portion 12 designed as a receptacle for thecapsule 11, and further comprises a handle 13.

FIG. 2 shows the interior of the extraction head 5 of the machine, witha receptacle 14 having guiding ramps 15 for guiding the capsule holder 8therein. Once the capsule holder and capsule 11 are inserted into thereceptacle 14, the extraction head of the machine is closed manually bythe user actuating the locking lever 7 downwardly, which moves a needleplate 16 down, towards the upper surface of the capsule 11 and capsuleholder 8. Doing this, a water injection needle 17 pierced through thetop membrane 18 of the capsule. At this time, the capsule isfunctionally enclosed within the extraction head, and its peripheralupper edge 19 is tightly held between the upper surface of the capsuleholder and the lower surface of the needle plate. The injection of waterfrom the reservoir, through the pump, optionally through the heatingelement, and via the needle of the machine, into the capsule, can start.

As shown in FIG. 3, the capsule 11 comprises capsule side walls 20 whichdefine a generally frusto-conical body closed at its bottom by a bottomwall 21 integrally formed with the body side walls 20. The centre of thebottom wall 21 comprises a dispensing opening (or outlet) 22 to let thebeverage prepared inside the capsule, flow out of said capsule into acup placed here below. The capsule further comprises a pierceablealuminum membrane 23 that is sealed inside the capsule, close to thebottom wall 21, as well as a piercing plate 24 for piercing saidaluminum membrane when pressure inside the capsule increases. Thealuminum membrane 23 has a barrier function to protect the capsulecontents against moisture and oxygen during storage.

The piercing plate is located between the aluminum membrane and thebottom wall of the capsule. Finally, the capsule is closed at its top bythe pierceable membrane 18. All walls and membranes define a chamber,into which a beverage precursor ingredient is placed, which is meant tobe mixed with the water injected through the water injection needle ofthe machine, as described above. The mix of the ingredient with themachine produces a beverage under pressure, that is dispensed when thecapsule opens. The opening of the capsule occurs when the pressureinside the capsule is sufficiently high to either flex the aluminummembrane towards the piercing plate 24, or sufficiently high to simplytear the aluminum membrane open. During storage, the capsule is made outof such materials that it is moisture and oxygen barrier.

The invention will now be described in more detail with reference toFIGS. 4 to 9.

In a first embodiment of the invention illustrated in FIGS. 4 to 8, thecapsule 11 further comprises a pressure-sensitive precut membrane 25having four non-reclosable precut slits 26 which:

(i) elastically and plastically widen when the fluid pressure insidesaid capsule reaches a predetermined value between 1 and 20 bar relativepressure, as illustrated in FIG. 7 and then

(ii) maintain a widen configuration after the fluid pressure within thechamber is released to an atmospheric pressure value, such that thewidth of each of said slits 26 does not exceed 1 mm.

As shown in FIG. 4 which is an exploded schematic partially cut view ofthe capsule, the precut membrane 25 is sealed adjacent to, or at a closedistance (i.e. less than 5 mm, preferably less than 2 mm, morepreferably less than 1 mm) from the aluminum membrane, and locatedbetween said aluminum membrane 23 and the ingredient contained withinthe capsule.

The precut membrane has the shape of a disc of thermoplastic film asillustrated in FIG. 5, so as to follow the general frusto-conical shapeof the capsule. It comprises four precut slits 26, spaced apart fromeach other and distributed across the surface of the membranepreferably—although not necessarily—at equal distances from each other.The slits have a length to width ratio comprised between 5:1 and 20:1.Their length is of about 3 to 5 mm, and they are located at a distanceof about 10 mm from the outer edge of the membrane.

The slits can be precut through the entire thickness of the membrane 25,or alternatively, they can be precut through only a portion of saidmembrane.

In that latter case, the slits are for instance precut by using a laserscoring technology, cutting through e.g. half of the thickness of themembrane 25, so as to establish a predetermined precut line of weaknessalong which the membrane will preferentially tear itself when a fluidpressure is built up inside the capsule. Such a configuration has theadvantage that the precut membrane can be made out of a multilayerlaminated thermoplastic material comprising at least one layer of athermoplastic that is easily sealable onto the inner surface of thecapsule side or bottom walls, and at least one material that is moistureand oxygen barrier, so as to guarantee a long shelf life for the capsuleand its contents. In that case, of course, the laser scoring isperformed such that the barrier layer of the membrane 25 is not cut, andthe precut is performed only through layer(s) which do(es) not have abarrier function. This removes the need for an additional aluminiumbarrier membrane.

Importantly, the material that was chosen for manufacturing the membrane25 is a polypropylene having a thickness comprised between 200 and 300μm, having a Young's modulus of about 1600 MPa and Yield limit of about30 MPa. Its melting point is about 160° C. Such characteristics ensurethat the precut slits open and widen under pressure and then reclosesufficiently to ensure that an anti-dripping effect is achievedaccording to the principles of the invention.

During storage of the capsule, and until said capsule is filled byinjected water under pressure, the precut membrane 25 and the slits 26are in the configuration shown in FIG. 6. In such a configuration, theprecut membrane 25 is located adjacent to the aluminium membrane 23, andthe slits 26 are in a closed configuration.

After the capsule 11 has been inserted into the capsule holder and thelatter is functionally inserted into the extraction head of the machine,as described above, the user can start a beverage preparation cycle asalready described. As described above, the preparation of a beverage isperformed by injecting under pressure a fluid (typically water) which isheated, or not, into the capsule through the injection needle thatprotrudes into the capsule chamber through the top membrane 18. As fluidis injected into the capsule chamber, a fluid pressure builds up insidethe capsule and presses against the capsule walls and membranes,especially against the precut membrane 25. The force exerted by thefluid under pressure pushes onto the lips of the slits which are widen(or torn open in case the membrane 25 was not cut through its wholethickness as described above), as illustrated in FIGS. 7 and 8. At thatstage, the aluminium membrane 23 (if one is present) is moved away fromthe precut membrane 25 as illustrated in FIG. 8. Then the fluid pressesonto the aluminium membrane if one is present, which is opened (bytearing, or by action of the piercing plate 24). The capsule is thenopened and the beverage is dispensed by gravity in a cup (not shown inthe drawing) placed below the capsule 11.

In a second embodiment of the invention illustrated in FIG. 9, thepressure-sensitive precut membrane 25 is not sealed adjacent to thealuminium membrane 23 as it was the case for the first embodimentdescribed above. The aluminium membrane 23 has a reduced surface and issealed outside of said capsule 11, onto the external surface of thebottom wall 21 of the capsule, so as to tightly cover and sealinglyclose the dispensing opening 22 of the capsule. Further, the capsuledoes not comprise a piercing plate as it was the case for the firstembodiment described above. In this case, the aluminium membrane is tornas the fluid pressure inside the capsule reaches a certain predeterminedlevel. The working principle of the pressure-sensitive precut membrane25 and the slits 26 is the same as described herein before withreference to the first embodiment of the invention.

The capsule according to the invention provides two beneficial effectsduring and after production of a beverage therein.

Firstly, the membrane with slits provides a filter effect that preventsbig particles of non-dissolved ingredient to flow into the consumer cup(due to the width of the slits which do not open sufficiently to letthese large particles out). The invention is particularly beneficial inthat this filter effect is obtained simultaneously to a dispensing flowrate which is sufficient to guarantee that a large volume of beverage isdispensed within a few seconds. Typically, a 250 ml long coffee cup canbe dispensed within less than 10 seconds, and an espresso coffee cup ofabout 60 ml can be dispensed within less than 5 seconds. This means thata minimal dispensing flowrate of 10 ml/sec, preferably 20 ml/sec, morepreferably 25 ml/sec can be achieved, while at the same time achieving afilter effect during the beverage dispensing phase which allows toretain particles larger than 2 mm, preferably larger than 1 mm, morepreferably larger than 500 μm.

Secondly, the membrane with slits provides an anti-dripping effect bycapillarity: when the injection of water stops, the pressure inside thecapsule is released, to a value which is substantially equal to theatmospheric pressure. At this time, the slits do not reclose completelydue to their plastic deformation during the beverage dispensing step.However their width is reduced sufficiently to provide a capillarityeffect, due to the elastic properties of their constitutive material,such that the remaining liquid inside the capsule does not drip bygravity, and is retained within the capsule.

The capsule top can be a plain membrane sealed to the top edges of thecapsule, that is preferably moisture and oxygen barrier. Alternatively,said capsule top can be a perforated membrane or a filter membrane.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its attendant advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1. A beverage capsule comprising capsule side walls, a capsule top, and a capsule bottom having a dispensing outlet, that define a chamber for containing a food or beverage precursor ingredient soluble and/or extractable when a fluid is injected inside the chamber under pressure, the capsule further comprising a pressure-sensitive membrane, the pressure-sensitive membrane comprises at least one weakened or precut zone defining a non-reclosable opening which: elastically and plastically opens, respectively widens when the fluid pressure inside the capsule reaches a predetermined value between 0.5 and 20 bar relative pressure; and maintains a widen configuration after the fluid pressure within the chamber is released to an atmospheric pressure value, such that the width of the at least one opening does not exceed 1 mm.
 2. A capsule according to claim 1, wherein the at least one precut opening is a slit having a length to width ratio of between 1:1 and 1000:1.
 3. A capsule according to claim 1, wherein the pressure-sensitive membrane is constructed from a material having the following physical characteristics: a Young's modulus within the range of 800 MPa to 5000 MPa, a Yield point within the range of 10 MPa to 50 MPa, and a melting point within the range of 100° C. to 200° C. and a thickness of between 50 μm and 800 μm.
 4. A capsule according to claim 1, wherein the pressure-sensitive membrane is constructed of at least one layer of a thermoplastic material, selected from the group consisting of: polyethylene, ethylene vinyl alcohol, polystyrene, and combinations thereof.
 5. A capsule according to claim 1, wherein the capsule side walls and capsule top are moisture and oxygen permeable, and wherein the capsule further comprises a pierceable or tearable moisture and oxygen barrier bottom membrane, such that the capsule chamber is closed.
 6. A capsule according to claim 5, wherein the bottom membrane is openable by piercing through action of a piercing element located within or outside of the capsule vicinity.
 7. A capsule according to claim 1, wherein the beverage prepared within the capsule has a viscosity of between 0.1 and 100 mPa·s.
 8. A capsule according to claim 1, which comprises a precursor ingredient for making a beverage selected from the group consisting of: soups, fruit juices, vegetable juices, bouillons, coffee, chocolate, tea, milk or creamer, and combinations thereof. 